[feature request] Add a "Username template importer" mapper for Identity provider

[mleneveut]

Hi,

I'd like to terraform the creation of the identity provider, but I can't figure out how to create a mapper type "Username Template Importer" for an identity provider.

I found this one for the Attribute Importer : https://mrparkers.github.io/terraform-provider-keycloak/resources/keycloak_attribute_importer_identity_provider_mapper/ but not for "Username Template Importer"

Thanks.

[CalamarBicefalo]

Maybe related to https://github.com/mrparkers/terraform-provider-keycloak/issues/429

Similar issue with the advanced claim to role mapper

[philipp1992]

did anyone find a solution for creating this kind of mapper?

[m-v-k]

Also need it. looked in the code to add it and found it actually already exists, but missing in docs. It works just fine, so added a pr for the docs #635